Darin was used to the sound and the feeling of being flanked. After all, he was technically still a wanted man, back home. He knows how soldiers work. He knows the distinct sounds of foot falls. All he needed was for Edelgard to drop her curse.

When she did, he acted. With a powerful surge of strength buffering magic sent to his leg, he lifts his foot and stomps with the force of a bomb going off; more than enough to shatter the ground beneath them and definitely enough to catch her little contingent off guard enough to knock them off their feet. Whether it does the same to Edelgard or not, he doesn't care. It'll take them at least a few minutes to get sure footing again and that's all he needed.

Fortunately, by this point, someone else seems to have intercepted the dragon's flight path. Darin doesn't know it yet, but it's a good friend of his. Using the lucky break, Darin turns his back on Edelgard.

"If I fail, then I fail, but I'm going to try whether you grant me permission or not, Your Majesty."

With that, he's off. If any blood mage attempts to use blood magic to slow him down, he'll counter with his own blood magic to cancel it. But he knows Edelgard won't follow.